Wyniki wyszukiwania - BazTech

1

Robust Optimal Dispatch of Power Systems with Wind Farm

Zhang Jinhua, Gu Bo, Meng Hang, Fu Chentao, Zhu Xueling

Journal of Power Technologies

|

2020

|

Vol. 100, nr 2

92--101

EN

With the rapid development of new energy power generation, large-scale wind power generation has been integrated into power grids. However, the fluctuation and discontinuity of wind power pose challenges to the safe and reliable operation of power systems. Therefore, constructing a reasonable dispatching method to manage the uncertainty of wind power outputhas become an important topic and this study was structured with this precise aim in mind. An ellipsoidal robust set of wind power outputs was initially constructed in accordance with the predicted value and predicted error of wind power. Second, a power system optimization dispatch model of automatic generation control (AGC) was established on the basis of the robust set. This model aimed to minimize the cost of power generation and maximize the use of wind power according to the following constraint conditions: power system power balance, upper andlower limit of wind and thermal power unit outputs, climbing power, and spinning reserve. Finally, the internal point method was employed to solve the example. Results show that, on the premise of safe operation, the total operating cost of the robust optimization dispatch method is decreased by 8.64% compared with that of the traditional dispatch method, and economic efficiency is improved. Robust optimal dispatch factors in the uncertainty of wind power output meaning the load shedding scenario seldom occurs, thereby enhancing operational reliability. This study can be used to improve the reliability and economics of power system operation and provide a basis for optimizing dispatch in power systems.

2

Wavelets and principal component analysis method for vibration monitoring of rotating machinery

Bendjama H., Boucherit M. S.

Journal of Theoretical and Applied Mechanics

|

2016

|

Vol. 54 nr 2

659--670

EN

Fault diagnosis is playing today a crucial role in industrial systems. To improve reliability, safety and efficiency advanced monitoring methods have become increasingly important for many systems. The vibration analysis method is essential in improving condition monitoring and fault diagnosis of rotating machinery. Effective utilization of vibration signals depends upon effectiveness of applied signal processing techniques. In this paper, fault diagnosis is performed using a combination between Wavelet Transform (WT) and Principal Component Analysis (PCA). The WT is employed to decompose the vibration signal of measurements data in different frequency bands. The obtained decomposition levels are used as the input to the PCA method for fault identification using, respectively, the Q-statistic, also called Squared Prediction Error (SPE) and the Q-contribution. Clearly, useful information about the fault can be contained in some levels of wavelet decomposition. For this purpose, the Q-contribution is used as an evaluation criterion to select the optimal level, which contains the maximum information.Associated to spectral analysis and envelope analysis, it allows clear visualization of fault frequencies. The objective of this method is to obtain the information contained in the measured data. The monitoring results using real sensor measurements from a pilot scale are presented and discussed.

3

Steganographic data hiding in image processing using predictive differencing

Weng C. Y., Tso H. K., Wang S. J.

Opto-Electronics Review

|

2012

|

Vol. 20, No. 2

126-133

EN

In this paper, we propose a stenography scheme based on predictive differencing to embed data in a grey-image. In order to promote the embedding capacity of pixel-value differencing (PVD), we use differencing between a predictive value and an input pixel as the predictive differencing to embed the message where a predictive value is calculated by using various predictors. If the predictive differencing is large, then it means that the input pixel is located in the edge area and, thus, has a larger embedding capacity than the pixel in a smooth area. The experimental result shows that our proposed scheme is capable of providing greater embedding capacity and high quality of stego-images then previous works. Furthermore, we have also applied various predictors to evaluate our proposed scheme.

4

Ocena możliwości ograniczenia liczby powtórzeń w badaniach trwałości zmęczeniowej

Piekoszowski W., Ruta R., Trzos M.

Tribologia

|

2009

|

nr 3

197-208

PL

W artykule przedstawiono wyniki badań ukierunkowanych na ocenę prognoz trwałości zmęczeniowej węzła tarcia. Analizie poddano wyniki badań pittingu. Zgodnie z procedurą badanie tego typu zużycia obejmuje wykonanie 24 biegów badawczych, co wymaga znacznego nakładu czasu oraz poniesienia znaczących kosztów związanych z eksperymentem. Głównym celem badań było oszacowanie możliwości skrócenia cyklu badawczego przy zachowaniu zadanego poziomu błędu. Badania eksperymentalne zrealizowano na zmodernizowanym stanowisku czterokulowym w Laboratorium Badań Tribologicznych ITeE – PIB. Przeprowadzono 37 serii eksperymentów badawczych, dla różnych skojarzeń materiałowych i środków smarowych. Jako kryterium oceny zbieżności wyników przyjęto błąd względny prognozy przy skróconym cyklu badawczym w odniesieniu do prognozy trwałości zmęczeniowej opracowanej na podstawie 24 biegów badawczych. Uzyskane wyniki potwierdziły zasadność podjętych badań wskazując przesłanki skrócenia cyklu badawczego oraz poszukiwania czynników mających wpływ na zbieżność prognoz.

EN

The article presents the results of research carried out to estimate the convergence of friction contact fatigue durability predictions. The fatigue wear of the pitting type was analysed. According to the procedure, the research series encompass 24 research operations that are usually time-consuming and increase experiment costs. The major aim of the presented research was to estimate the possibilities of shortening the research procedure while the error of such approximation can be accepted. The experimental research was conducted on the modernized four-ball apparatus in the Tribological Research Laboratory of the Institute for Sustainable Technologies – NRI in Radom. The 37 research experiments were carried out for different materials and lubricants. As the criterion of research results, convergence the relative error of the shortened procedure fatigue prediction and 24 courses procedure prediction was established. The analysis of experimental results shows the premises to shorten the research procedure and arguments for research of factors that influence prediction convergence.

5

Video coding using redundant dictionary of base functions

Saganowski Ł.

Elektronika : konstrukcje, technologie, zastosowania

|

2009

|

Vol. 50, nr 3

14-18

EN

In this paper video coder with Base Function Dictionary - BFD has been presented. In classic approach prediction error signal is encoded with block based transformation such as popular Discrete Cosine Transform - OCT. The coder proposed in this article uses BFD dictionary to encode prediction error signal. BFD has been adapted to prediction error signal characteristic.

PL

W artykule przedstawiony został Koder Obrazów Wideo z użyciem Słownika Funkcji Bazowych - SFB. W standardowych rozwiązaniach sygnał błędu predykcji kodowany jest z użyciem transformacji OCT. W zaproponowanym koderze wideo błąd predykcji zakodowany został z użyciem Słownika Funkcji Bazowych. SFB został zaadaptowany do charakterystyki sygnału błędu predykcji.